Execute cronjob just once per day
Use pingdom summary API to fetch latency and uptime data

This is very effective request-wise. It costs around 1 + <amount of
checks> to get the latency and uptime info.

Currently this is performed once per day using cron although that can be
changed if needed.

Note that the frontend still needs to be updated to use the new data
format. It is more compact than the previous one. There still could be
some problems in it, though.
Remove extraneous ;
Simplify generated JSON structure
Format uptime data in a nicer way

They are floats now. Also scaled by 100 so that the figures are correct.
Hook up new data model with the frontend

Note that there is still a date related bug around. firstDate and
lastDate should be used. In case there is not enough data, generate
empty entries (zero for latency, one for uptime).
Rename firstDay and lastDay to firstDate and lastDate

Just to be consistent.
Hook up lastDate with labels
Generate zeroes front of dataset in case data is missing